What does Class 0.5 vs Class 1 mean on a CT?

Class is the accuracy tolerance. Class 0.5 means ±0.5% error, used for utility billing and tariff metering. Class 1 means ±1%, fine for sub-metering, panel metering and internal audit.

Do you supply CTs with custom ratios?

Yes — Lauritz Knudsen (L&K) CTs are available in custom ratios (e.g. 100/5A, 200/5A, 500/5A, 1000/5A). Share your feeder current and meter input (5A or 1A secondary) and we confirm the SKU.

Is IS 2705 compliance mandatory?

For utility and billing installations, yes. Lauritz Knudsen (L&K) CTs are IS 2705 compliant. For internal panel metering it's recommended but not mandated.

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Category · Current Transformers

LT Current Transformer (CT) Supplier in Chennai — Lauritz Knudsen (L&K) Class 0.5 / 1

Panel metering, energy audit, feeder measurement — low-tension current transformers from Lauritz Knudsen (L&K). Class 0.5 and Class 1 accuracy, IS 2705 compliant, custom ratios on request.

Browse Lauritz Knudsen (L&K) range Custom ratio quote

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CT specs

Accuracy: Class 0.5 (billing / utility) or Class 1 (panel / audit).
Ratio: Custom primary (100A, 200A, 500A, 1000A, 2000A) / 5A or 1A secondary.
Compliance: IS 2705.
Applications: Panel metering, motor feeders, submain, energy audit.
Type: Window-type (bus-bar through), wound primary on request.

How to size a CT

Identify the feeder's full-load current (e.g. 400A feeder).
Select primary rating equal to or slightly above full load (use 500/5A for 400A feeder).
Match secondary to meter input (most Lauritz Knudsen (L&K) panel meters: 5A secondary).
Choose Class — 0.5 for billing, 1 for panel display / audit.

FAQ

Is CT polarity important?

Yes — P1/P2 on primary and S1/S2 on secondary must be connected correctly for the meter to read positive power. Reversed CT shows negative kWh.

Can I use one CT with multiple meters?

Yes — daisy chain the secondary through multiple meters in series. Ensure total burden (VA of all meters + cable) stays within CT's rated burden.

Do you supply summation CTs or ring-core CTs?

On request. Share the application (three-phase summation, earth fault, residual current) and we recommend the right variant.